Oil well heating system



F. c. RIPLEY, JR 2,914,124

OIL WELL HEATING SYSTEM Nov. 24, 1959 Filed July 17; 1956 2 Sheets-Sheet 1 far/are ,yea/er Uni) 270w [live We 6 240 IN VEN TOR.

DJMAAM Nov. 24, 1959 F. c. RIPLEY, JR

OIL WELL HEATING SYSTEM 2 Sheets-Sheet 2 Filed July 17, 1956 fmze/cz 6.36 4554 J.

INVENTOR.

BY )1 k Q 964w:

United States Patent on. WELL HEATING SYSTEM Frederick C. Ripley, Jr., Rolling Hills, Calif., assignor to Oil Well Heating Systems, Incorporated, Los Angeles, Calif., a corporation of California Application July 17, 1956, Serial No. 598,338

4 Claims. (Cl. 166-57) This invention relates to oil-well heaters, and more particularly to an improved method and'device for applying heat at the bottom'of a well so as to facilitate production thereof.

It is well-known that 'a limiting factor in producing oil from a well is the viscosity of the oil, and often additionally the precipitation of waxy and asphaltic material from the produced oil, particularly in the region where the oil enters the bore hole. A means of facilitating production which has been restricted from these causes is the application of heatto the well. The heat is '10- calized most generally opposite the producing formation itself, and particularly at the point where the well pump is located, but in many cases it is desirable to apply heat also farther up the hole. ,By raising the temperature of the oil in the well and in the region immediately surrounding the well in the producing formation itself, the viscosity of the oil is lowered, and waxy or asphaltic materials which might otherwise "appear are kept liquefied or dissolved in the oil or both.

Application of heat to wells in the general manner mentioned has been practiced for many years. However, improvement is still desired in the efiiciency of which heat is applied to the selected portions of the well, in reducing heat wasted to other portions of the well where little is accomplished by the heating process, and in the mechanical ease and certainty with which the heating system can be assembled and introduced into the well.

An object of the present invention is to provide an oilwell heating system whereby heat can be applied locally within a well bore with a minimum wastage of heat.

Another object of the invention is to provide a well heater of simplified mechanical construction.

Other objects of the invention will appear as the description thereof proceeds.

In the drawings,

Fig. l is a general view of the inventive system as used in a producing oil well.

Fig. 2 is an enlarged cross-section of a selected upper portion of theheating assembly.

Fig. 3 is an enlarged cross-section of a selected lower portion of the heating assembly.

Referring now to Fig. 1 this shows a well bore 1, traversing a number of strata including an exemplary producing stratum 2. The well is cased with a casing 3, and oil produced in the well is pumped by a conventional pump 4 through a gas anchor 5 and through production tubing 6 in a well-known manner In the illustrative embodiment, the main portion of the down-the-hole assembly is shown attached to the lower end of the production string, at the joint 7. This down-the-hole assembly 8 comprises an elongated outer tubing 9 containing two inner tubings or pipes 10 and 11, as may be seenfrom Figs. 2-and 3. Tubing 9 is closed at the upper end by a sealing plate 28.

Fig. 2 shows the portion of the heating assembly be- Patented Nov. 24, 1959 tween the upper portion of tubing 9 and the connecting joint 7; while Fig. 3 shows in detail the portion of the heating assembly at the lower end of tubing 9. It will be understood that the top portion of the structure of Fig. 3 is a continuation of the lower portion of Fig. 2, since the down-the-hole assembly may be elongated as desired and in particular as required by the height of the bottom of the production tubing from the producing sand or other selected portions of the well to be heated, this may be a great many feet, indeed several hundred or thousand 7 feet, and accordingly the broken portions of Figs. 2 and sub 12 is attached to the outer tube 9 conveniently by a coupling 17 having its upper threads left hand and its lower threads right hand. The lower portion of injection tubulation 13 is connected to a spacer sub 18, which provides threading engagement for inner pipes 10 and 11, in such a manner that the latter are maintained more or less concentric and hermetically sealed at the threaded points within sub 18. It will be understood that in accordance with usual oil field practice, semi-solid sealing compounds, commonly known as pipe dopes will be used in making up all threaded joints, so that they will form hermetic seals.

It will be understood that the various tubings 9, 10 and 11 will be made up of joints of pipe joined by couplings or sleeves in the conventional fashion; some of the latter are shown in the drawings.

The lower end of'inner tubing 10 is capped by a lower adapted sub 19 by screw thread engagement. Lower adapter sub 19 is bored to an inner diameter slightly greater than the outer diameter of inner tubing 11, and this bored portion of lower adapter sub 19 is grooved to receive a multiplicity of O-rings 20, which should be made of oil-resistant rubber. I have found it desirable to subject the lower-most portion of inner tubing 11 to a grinding or honing operation so that it presents a very smooth, highly circular outer surface for two or three feet of its terminal portion, and moreover to chamfer the lower end thereof as shown in Fig. 3. Conveniently also, I provide a tapered portion 21 just above the boredout portion of adapter sub 19, so as to facilitate the entry of inner tube 11 into that portion of adapter sub 19. The assembly so described provides for a hermetically tight seal between inner tubes 10 and 11 at the lower end of the assembly, and at the same time permits relative motion of tube 11 longitudinally with respect to inner tube 10, which is especially facilitated by the smooth outer surface of the outer portion of inner tube 10 at the portion generally in contact with the O-rings 20. This action is necessary because inner tube 11 will expand more than inner tube 10 when the device is in operation, because of the generally higher temperature of the former. My device is assembled in such a way that only air or other insulator is included in the space between inner tubes 10 and 11, and the construction shown effectively excludes the entry of liquids into this annular is connected to a surface heater unit 25 bymeans of an injection line 26; and return pipe 16 is similarly connected to the heater unit 25 by a return line 27.

Any desired fluid may be used as a heat-transfer medium. Water is most generally suitable. An alternative heat-transfer liquid is oil, such as ordinary diesel 'oil,

kerosene or the like. Other heat-transfer liquids can be used, .such as diphenyl, hydrogenated naphthalene, various chlorinated hydrocarbons, gallium metal, various alkalimetal alloys, especially eutectic mixtures thereof, and the like.

In the operation of my well-heating system, the heattransfer liquid is both heated and propelled by the surface heater unit 25 so as to maintain circulation of hot liquid through injection line 26 into injection pipe 15. The fluid passes downwardly through tubulation 13 into inner tube 11 and thence to the lower end of the assembly, where it issues from the bottom of inner tube .11 and flows upwardly in the annular space between the outside ofinner tube and the inside of tube 9. Flowing upwardly, it traverses the outside of sub 18 and flows through tubulation 1-4 into return pipe 16, whence it returns to the surface heater unit 25 by return line 27. The surface heater unit 25 may be any suitable combination of heater and pump, such as a steam-heated, gasor oil-fired or electrically heated device adapted to liquid heating, and any kind of pump, such as centrifugal, piston, rotary vane, or the like, so as to propel the heated liquid into injection line 26.

It will be seen that the invention accomplishes its objects. The lower end of tubing 9 may be positioned wherever application of heat is needed most, as determined by the conditions obtaining in the well. On the other hand, there is minimum loss of heat from the heattransfer liquid from the time that it leaves the heater unit 25 until the time that it is released at the lower end of tubing 9in order to heat the well by heat transfer across the lower portion of tubing 9 and thence into and through any liquids surrounding the lower portion of tubing 9 in the well. Surface lines 26 and 27 will of course be lagged in the usualfashion, such as by using magnesia-asbestos or rock wool lagging'or other thermal insulators so that surface heat losses can be maintained at a minimum. By far the greatest portions of the lengths ofinjection pipe and return pipe 16 are in the relatively dead space between the production tubing 6 and the casing 3, surrounded only by air and gas, so that heat losses here are at a minimum. In the upper and intermediate portion of the well bore traversed by tubing 9, wherein tubing 9 is surrounded by oil passing from the producing formation 2 to the well pump 4, loss ofheat from the heat-transfer liquid is prevented by the air space formed and maintained between inner tubes 10 and 11, in the fashion described.

While specific embodiments of the invention have been shown and described herein, it will be apparent that the invention is a broad one, and numerous modifications therein may be made within the scope of this disclosure and the claims which follow:

What I claim is:

1. A heating system for use in an oil well, comprising in combination: liquid heating means; liquid propulsion means; an elongated housing tube closed at both ends positioned in the well with at least the lower portion thereof adjacent to those parts of said well to be heated; a first inner tube within said housing tube; a second inner tube within said-first inner tube and generally coextensive and concentric therewith; a first tubulation communicating from th upper portion of said housing tube to the exterior thereof; a second tubulation positioned in the topportion of said housing. tube and communicating from the exterior thereof and passing through the interior thereof, communicating with and joined to the upper end of said second inner tube; sealing means establishing a -hermetic seal between the upper ends of said first and second inner tubes; sealing means at the lower end of said first inner tube establishing a seal about the lower end of said second inner tube without restraining relative longitudinal movement of said first and second inner tubes; conduit means between said first tubulation and said liquid heating and liquid propulsion means; and conduit means between said second tubulation and said liquid heating and liquid propulsion means.

2. A heating system for-use in an oil well, comprising in combination: liquid heating means; liquid propulsion means; a production. tubing assembly .in said well and bearing a pump in th'e lower portion thereof; an elongated housing tube closed at both ends positioned in the well by attachmentat the upper end thereof to the lower end of said production tubing assembly with at least the lower portion of said housing tube adjacent to those parts of said well to be heated; a first inner tube within said housing tube; a second inner tube within said first inner tube and generally coextensive and concentric therewith; a

.first tubulation communicating from the upper portion passing through the interior thereof, communicating with .and joined to the upper end of .said second inner tube;

sealing means establishing a hermetic seal between the upper ends of said first and second inner tubes; sealing means at thelower end of said firstinner, tube establishing .a seal about the lower end of said second inner tube without restraining relative longitudinal movement of said first and second inner tubes; conduit means between said first tubulation and said liquid heating and liquid propulsion means; and conduit means between said second tubulation and said liquid heating and liquid propulsion means.

3. .A heating system for use in an oil well, comprising in combination: liquid heating means; liquid propulsion means; an elongated housing tube closed at both endspositioned in the well with at least the lower portion thereof adjacent to those parts of said well to be heated; a first inner tube within sai housing tube; a second inner tube within said first inner tube and gen erally coextensive and concentric therewith; a first tubulation communicating from the upper portion of said housingtube to the exterior thereof; a second tubulation positioned in the top portion of said housing tube and communicating from the exterior thereof and passing through the interior thereof, communicating with and joined to the upper end of said second inner tube; sealing means establishing a hermetic seal between the up per ends of said first and second inner tubes; an adapter at the lower end of said first inner tube slidably receiving the lower end of said second inner tube; O-ring sealing means positioned within said adapter and engaging the outer surface of said lower end of said second inner tube; conduit means between said first tubulation and said liquid heating and liquid propulsion means; and conduit means between said second tubulation and said liquid heating and liquid propulsionmeans.

4. A heating system for use in an oil well, comprising in combination: liquid heating means; liquid propulsion means; a production tubing assembly in said well and bearinga .pump-in the lower portion thereof; an elongated housing tube closed at both ends positioned in the Well byattachment'atthe upper end thereof to the lower endofsaid production. tubing assembly with at least the lower portion of said housing tube adjacent to those parts of said well to be" heated; at first inner tube within said housing tube; a second :inner tube within said first inner tubeand generally coextensive and concentric therewith; a first tubulation communicating from the upper portion of said housing tube to the exterior thereof; a second "tubulation position in the top portion of said housing tube and communicating from the exterior thereof and passing throughthe interior thereof, communicating with and joined to the upper end of said second inner tube; sealing means establishing a hermetic seal between the upper ends of said first and second inner tubes; an adapter at the lower end of said first inner tube slidably receiving the lower end of said second inner tube; 5 (ring sealing means positioned within said adapter and engaging the outer surface of said lower end of said second inner tube; conduit means between said first tubulation and s: d liquid heating and liquid propulsion means; and conduit means between said second tubula- 10 tion and said liquid heating and liquid propulsion means.

References Cited in the file of this patent UNITED STATES PATENTS 

